And if you’re interested in looking back, here’s an archive to all the past Carnivals of Space. If you’ve got a space-related blog, you should really join the carnival. Just email an entry to [email protected], and the next host will link to it. It will help get awareness out there about your writing, help you meet others in the space community – and community is what blogging is all about. If you’ve got a space-related blog, you should really join the carnival. Just email an entry to [email protected], and the next host will link to it. It will help get awareness out there about your writing, help you meet others in the space community – and community is what blogging is all about. And if you really want to help out, sign up to be a host. Send an email to the above address.
Yuma Outlook at Santa Maria Crater on Sol 2476, Jan 10, 2011. Opportunity arrived at the hydrated mineral deposits located here at the southeast rim of the crater. Self portrait of Opportunity at left, casts shadow of rover deck and mast at right. Credit: NASA/JPL/Cornell, Marco Di Lorenzo, Kenneth Kremer High resolution version on APOD, Jan. 29, 2011 ; http://apod.nasa.gov/apod/ap110129.html
Opportunity made landfall at the western edge of Santa Maria on Dec. 15, 2010 (Sol 2450) after a long and arduous journey of some 19 kilometers since departing from Victoria Crater nearly two and one half years ago in September 2008. Santa Maria is the largest crater that the rover will encounter on the epic trek between Victoria and Endeavour.
Robotic arm at work on Mars on Sol 2513, Feb 17, 2011. Opportunity grinds into rock target Luis De Torres’ with the RAT. Credit: NASA/JPL/CornellThe science team decided that Santa Maria would be the best location for an intermediate stop as well as permit a focused science investigation because of the detection of attractive deposits of hydrated minerals. The stadium sized and oval shaped crater is some 80 to 90 meters wide (295 feet) and about nine meters in depth.
Opportunity has since been carefully driven around the lip of the steep walled crater in a counterclockwise direction to reach the very interesting hydrated sulfates on the other side. The rover made several stops along the way to collect long baseline high resolution stereo images creating 3 D digital elevation maps and investigate several rocks in depth.
Opportunity was directed to Santa Maria based on data gathered from Mars orbit by the mineral mapping CRISM spectrometer – onboard the Mars Reconnaissance Orbiter (MRO) – which indicated the presence of exposures of water bearing sulfate deposits at the southeast rim of the crater.
Opportunity rover panoramic photomosaic near lip of Santa Maria Crater on Sol 2519, Feb. 23, 2011. Opportunity drove to exposed rock named Ruiz Garcia to investigate hydrated mineral deposits located here at southeast portion of crater. Credit: NASA/JPL/Cornell, Kenneth Kremer, Marco Di Lorenzo
“Santa Maria is a relatively fresh impact crater. It’s geologically very young, hardly eroded at all, and hard to date quantitatively,” said Ray Arvidson from Washington University in St. Louis. Arvidson is the deputy principal investigator for the Spirit and Opportunity rovers.
The rover had to take a pause anyway in its sojourn to Endeavour because of a restrictive period of solar conjunction. Conjunction is the period when the Sun is directly in between the Earth and Mars and results in a temporary period of communications disruptions and blackouts.
During conjunction – which lasted from Jan. 28 to Feb. 12 – the rover remained stationary. No commands were uplinked to Opportunity out of caution that a command transmission could be disrupted and potentially have an adverse effect.
Advantageously, the pause in movement also allows the researchers to do a long-integration assessment of the composition of a selected target which they might not otherwise have conducted.
By mid-January 2011, Opportunity had reached the location – dubbed ‘Yuma’ – at the southeast rim of the crater where water bearing sulfate deposits had been detected. A study of these minerals will help inform researchers about the potential for habitability at this location on the surface of Mars.
Opportunity at rim of Santa Maria crater as imaged from Mars orbit on March 1, 2011, Sol 2524.
Rover was extending robotic arm to Ruiz Garcia rock as it was imaged by NASA’s MRO orbiter.
Credit: NASA/JPL-Caltech/Univ. of Arizona
The rover turned a few degrees to achieve a better position for deploying Opportunity’s robotic arm, formally known as the instrument deployment device or IDD, to a target within reach of the arms science instruments.
“Opportunity is sitting at the southeast rim of Santa Maria,” Arvidson told me. “We used Opportunity’s Rock Abrasion Tool (RAT) to brush a selected target and the Moessbauer spectrometer was placed on the brushed outcrop. That spot was named ‘Luis De Torres’, said Arvidson.
Ruiz Garcia rock imaged by pancam camera on Sol 2419. Credit: NASA/JPL/Cornell‘Luis De Torres’ was chosen based on the bright, extensive outcrop in the region in which CRISM sees evidence of a hydrated sulfate signature.”
Opportunity successfully analyzed ‘Luis De Torres’ with all the instruments located at the end of the robotic arm; including the Microscopic Imager (MI), the alpha particle X-ray spectrometer (APXS) and then the Moessbauer spectrometer (MB) for a multi-week integration of data collection.
After emerging in fine health from the conjunction, the rover performed a 3-millimeter deep grind on ‘Luis De Torres’ with the RAT in mid-February 2011 to learn more about the rocks interior composition. Opportunity then snapped a series of microscopic images and collected spectra with the APXS spectrometer.
The rover then continued its counterclockwise path along the eastern edge of the crater, driving northwards some 30 meters along the crater rim to a new exposed rock target – informally named ‘Ruiz Garcia’ to collect more APXS spectra and microscopic images. See our mosaic showing “Ruiz Garcia” at the lip of the crater (above).
Opportunity finished up the exploration of the eastern side of Santa Maria in March by snapping a few more high resolution panoramas before resuming the drive to Endeavour crater which lies some 6.5 kilometers (4 miles) away.
Endeavour is Opportunity’s ultimate target in the trek across the Martian dunes because it possesses exposures of a hitherto unexplored type of even more ancient hydrated minerals, known as phyllosilicates, that form in neutral water more conducive to the formation of life.
Raw image from Opportunity's front hazard-avoidance camera on Sol 2524 ( March 1, 2011)
showing the robotic arm extended to Ruiz Garcia rock target. Credit: NASA/JPL/Cornell
The dark flow hypothesis. A region of the observable universe is being influenced by a mysterious something outside the observable universe. Source: universe-review.ca
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The hypothetical dark flow seen in the movement of galaxy clusters requires that we can reliably identify a clear statistical correlation in the motion of distant objects which are, in any case, flowing outwards with the expansion of the universe and may also have their own individual (or peculiar) motion arising from gravitational interactions.
For example, although galaxies have a general tendency to rush away from each other as space-time expands between them, the Milky Way and the Andromeda Galaxy are currently on a gravitationally bound collision course.
So, if you are interested in the motion of the universe at a large scale, it’s best to study bulk flow – where you step back from consideration of individual objects and instead look for general tendencies in the motion of large numbers of objects.
Very large scale observations of the motion of galaxy clusters were proposed by Kashlinsky et al in 2008 to indicate a region of aberrant flow, inconsistent with the general tendency in the motion and velocity expected by the expansion of the universe – and which cannot be accounted for by localized gravitational interactions.
On the basis of such findings, Kashlinsky has proposed that inhomogeneities in the early universe may have existed prior to cosmic inflation – which would represent a violation of the currently favored standard model for the evolution of the universe, known as the Lambda Cold Dark Matter (Lambda CDM) model.
The aberrant bulk flow might result from the existence of a large concentration of mass beyond the edge of the observable universe – or heck, maybe it is another adjacent universe. Since the cause is unknown – and perhaps unknowable, if the cause is beyond our observable horizon – the astronomical interrobang ‘dark’ is invoked – giving us the term ‘dark flow’.
To be fair, a lot of the more ‘out there’ suggestions to account for these data are made by commentators of Kashlinsky, rather than Kashlinsky and fellow researchers themselves – and that includes use of the term dark flow. Nonetheless, if the Kashlinsky data isn’t rock solid, all this wild speculation becomes a little redundant – and Occam’s razor suggests we should continue assuming that the universe is best explained by the current standard Lambda CDM model.
The apparent aberrant 'dark flow' (between the constellations of Centaurus and Vela) is alleged to show up in both close and distant galaxy clusters - where red is most distant, blue is least distant. This would suggest it is something that has been there since the universe was very young. Credit: Kashlinsky, NASA.
The Kashlinsky interpretation does have its critics. For example, Dai et al have provided a recent assessment of bulk flow based on the individual (peculiar) velocities of type 1A supernovae.
The Kashlinsky analysis is based on observations of the Sunyaev–Zel’dovich effect – which involves faint distortions in the cosmic microwave background (CMB) resulting from CMB photons interacting with energetic electrons – and these observations are only considered useful for identifying and observing the behavior of very large scale structures such as galaxy clusters. Dai et al instead use specific data points – being standard candleType 1a supernovae observations – and look at the statistical fit of these data to the expected bulk flow of the universe.
So, while Kashlinsky et al say we should ignore the motion of individual units and just look at the bulk flow – Dai et al counter with saying we should look at the motion of individual units and determine how well those data fit an assumed bulk flow.
It turns out that Dai et al find the supernovae data can fit the general trend of bulk flow proposed by Kashlinsky – but only in closer (low red shift) regions. More significantly, they are unable to replicate any aberrant velocities. Kashlinsky measured an aberrant bulk flow of more than 600 kilometers a second, while Dai et al found velocities derived from Type 1a supernovae observations to best fit a bulk flow of only 188 kilometers a second. This is a close fit with the bulk flow expected from the Lambda CDM model of the expanding universe, which is around 170 kilometers a second.
Either way, it’s all down to a statistical analysis of general tendencies. More data would help here.
Herschel's look at the Southern Cross. Credits: ESA and the PACS consortium
[/caption]For the lucky residents of the Southern Hemisphere, or those fortunate enough to enjoy a vacation in Hawaii or Cancun, there’s a stellar delight that few Northerners know about. It’s called the Southern Cross, a small but beautiful constellation located in the southern sky, very close to the neighboring constellation of Centaurus. Originally known by the Latin name Crux, which is due to its cross shape, this constellation is one of the easiest to identify in the night sky. For centuries, it has served as a navigational beacon for sailors, an important symbol to the Egyptians, and played an important role in the spiritual beliefs of the Aborigines and many other cultures in the Southern Hemisphere.
The first recorded example of Crux’s discovery was around 1000 BC during the time of the Ancient Greeks. At the latitude of Athens, Crux was clearly visible, though low in the night sky. At the time, the Greeks identified it as being part of the constellation Centaurus. However, the precession of the equinoxes gradually lowered its stars below the European horizon, and they were eventually forgotten by the inhabitants of northern latitudes. Crux fell into anonymity for northerners until the Age of Discovery (from the early 15th to early 17th centuries) when it was rediscovered by Europeans. The first to do so were the Portuguese, who mapped it for navigation uses while rounding the southern tip of Africa. During this time, Crux was also separated from Centaurus, though it is not altogether clear who was responsible. Some attribute it to the French astronomer Augustin Royer who did it in 1679 while others believe it was Dutch astronomer PetrusPlancius who did the deed in 1613. Regardless, it is believed to have taken place in the 17th century, placing it within the context of European expansion and the revolution that was taking place in the sciences at the time.
In terms of cultural significance, the Crux, like all constellations, played an important role in the belief system of many cultures. In the ancient mountaintop village of Machu Picchu, a stone engraving exists which depicts the constellation. In addition, in Quechua (the language of the Incas) Crux is known as “Chakana”, which literally means “stair”, and holds deep symbolic value in Incan mysticism (the cross represented the three tiers of the world: the underworld, world of the living, and the heavens). To the Aborigines and the Maori, Crux is representative of animist spirits who play a central role in their ancestral beliefs. To the ancient Egyptians, Crux was the place where the Sun Goddess Horus was crucified, and marked the passage of the winter season. The Southern Cross is also featured prominently on the flags of several southern nations, including Australia, Brazil, New Zealand, Papua New Guinea, and Samoa.
We have written many articles about the Southern Cross constellation for Universe Today. Here’s an article about Crux, and here’s an article about constellations.
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It was just over a century ago that a little known French scientist named Henri Becquerel came across something new and immensely startling. At the time, while working with phosphorescent materials (i.e. materials that glow in the dark after being subjected to light), he discovered naturally occurring rays that he couldn’t account for. In time, these rays were discovered to be present in several naturally occurring elements, and were dubbed radioactivity. Those metals that exhibited them also came to be known as Radioactive Isotopes.
Radioisotopes, (also known as radioactive isotopes or radionuclides), are atoms with a different number of neutrons than a usual atom. Due to this imbalance, these isotopes have an unstable nucleus that decays, and in the process emitting alpha, beta and gamma rays until the isotope reaches stability. Once it’s stable, the isotope has transformed into another element entirely. Every chemical element has one or more radioisotopes, with over 1,000 isotopes accounted for in total. Approximately 50 of these are found in nature; the rest are produced artificially as the direct result of nuclear reactions or indirectly as the radioactive descendants of these products.
Of the naturally occurring radioisotopes, there are three categories that are used to group them. The first is primordial radionuclides, which originate mainly within the interior of stars and like uranium and thorium, are still present because their half-lives are so long that they have not yet completely decayed. The second group, secondary radionuclides, are radiogenic isotopes derived from the decay of primordial radionuclides and are characterized by their shorter half-lives. The third and final group is known cosmogenic radionuclides, which consists of isotopes like Carbon 14 which are constantly produced in the atmosphere due to cosmic rays. Artificially produced radionuclides, on the other hand, are produced by nuclear reactors, particle accelerators or by radionuclide generators (where a parent isotope, usually produced in a nuclear reactor, is allowed to decay to produce a radioisotope). In addition, nuclear explosions are known to produce artificial radioisotopes as well.
Radioisotopes are used today for a variety of purposes. When it comes to the field of nuclear medicine, radioactive isotopes are used in MRI’s and X-rays for diagnostic purposes, for targeted radiation therapy, and to sterilize medical equipment. In biochemistry and genetics, radionuclides are used in molecular and DNA research in order to “label” molecules and trace chemical and physiological processes. Carbon-14, a naturally occurring cosmogenic isotope, is used for carbon dating by archeologists, paleontologists, and geologists. In agriculture, radiation is used to stop the sprouting of root crops, kill parasites and pests, and in veterinary medicine. And when it comes to industry, radionuclides are used to study the rate of wear and corrosion of metals, to test for leaks and seams, analyze pollutants, study the movement of surface water, measure water runoffs from rain and snow, and the flow rates of streams and rivers.
We have written many articles about radioisotopes for Universe Today. Here’s an article about isotopes, and here’s an article about radioactive decay.
[/caption]In the world of physics, there are few people who have been more influential than Sir Isaac Newton. In addition to his contributions to astronomy, mathematics, and empirical philosophy, he is also the man who pioneered classical physics with his laws of motion. Of these, the first, otherwise known as the Law of Inertia, is the most famous and arguably the most important. In the language of science, this law states that: Every body remains in a state of constant velocity unless acted upon by an external unbalanced force. This means that in the absence of a non-zero net force, the center of mass of a body either remains at rest, or moves at a constant velocity. Put simply, it states that a body will remain at rest or in motion unless acted upon by an external and unbalanced force.
Prior to Aristotle’s theories on inertia, the most generally accepted theory of motion was based on Aristotelian philosophy. This ancient theory stated that, in the absence of an external motivating power, all objects on Earth would come to rest and that moving objects only continue to move so long as long there is a power inducing them to do so. In a void, no motion would be possible since Aristotle’s theory claimed that the motion of objects was dependent on the surrounding medium, that it was responsible for moving the object forward in some way. By the Renaissance, however, this theory was coming to be rejected as scientists began to postulate that both air resistance and the weight of an object would play a role in arresting the motion of that object.
Further advances in astronomy were another nail in this coffin. The Aristotelian division of motion into “mundane” and “celestial” became increasingly problematic in the face of Copernicus’ model in the 16th century, who argued that the earth (and everything on it) was in fact never “at rest”, but was actually in constant motion around the sun.Galileo, in his further development of the Copernican model, recognized these problems and would later go on to conclude that based on this initial premise of inertia, it is impossible to tell the difference between a moving object and a stationary one without some outside point of comparison.
Thus, though Newton was not the first to express the concept of inertia, he would later refine and codify them as the first law of motion in his seminal work PhilosophiaeNaturalis Principia Mathematica (Mathematical Principals of Natural Philosophy) in 1687, in which he stated that: unless acted upon by a net unbalanced force, an object will maintain a constant velocity. Interestingly enough, the term “interia” was not used in the study. It was in fact JohanneKepler who first used it in his Epitome AstronomiaeCopernicanae (Epitome of Copernican Astronomy) published from 1618–1621. Nevertheless, the term would later come to be used and Newton recognized as being the man most directly responsible for its articulation as a theory.
We have written many articles about the law of inertia for Universe Today. Here’s an article about Newton’s Laws of Motion, and here’s an article about Newton’s first law.
If you’d like more info on the law of inertia, check out these articles from How Stuff Works and NASA.
We’ve also recorded an entire episode of Astronomy Cast all about Gravity. Listen here, Episode 102: Gravity.
[/caption]In the last few centuries, in which time we have had several scientific revolutions, our understanding of heat, energy and the exchange thereof has grown exponentially. In particular has been the increasing ability to gauge the amounts of energy involved in particular processes and in turn create theoretical frameworks, units, and even tools with which to measure them. One such concept is the measurement known as Emissivity. Essentially, this is the relative ability of a material’s surface (usually written ? or e) to emit energy as radiation. It is expressed as the ratio of the emissivity of the material in question to the radiation emitted by a blackbody (an idealized physical body that absorbs all incident electromagnetic radiation) at the same temperature. This means that while a true black body would have an emissivity value of 1 (? = 1), any other object, known as a “grey body”, would have an emissivity value of less than 1 (? < 1).
In general, the duller and blacker a material is, the closer its emissivity is to 1. The more reflective a material is, the lower its emissivity. Emissivity also depends on such factors as temperature, emission angle, and wavelength of the radiation. At the opposite end of the spectrum is the material’s absorptivity (or absorptance), which is the measure of radiation absorbed by a material at a particular wavelength. When dealing with non-black surfaces, the relative emissivity follows Kirchhoff's law of thermal radiation which states that emissivity is equal to absorptivity. Essentially an object that does not absorb all incident light will also emit less radiation than an ideal black body.
An important function for emissivity has to do with the Earth’s atmosphere. Like all other “grey bodies”, the Earth’s atmosphere is able to absorb and emit radiation. The overall emissivity of Earth's atmosphere varies according to cloud cover and the concentration of gases that absorb and emit energy in the thermal infrared (i.e. heat energy). In this way, and by using the same criteria by which they are able to calculate the emissivity of “grey bodies”, scientists are able to calculate the amount of thermal radiation emitted by the atmosphere, thereby gaining a better understanding of the Greenhouse Effect.
Every known material has an emissivity coefficient. Those that have a higher coefficient tend to be polished metals, such as aluminum and anodized metals. However, certain materials that are not metals and are non-reflective, such as red bricks, asbestos, concrete and pressed carbon, have equally high coefficients. In addition, naturally occurring materials such as ice, marble, and lime also have high emissivity coefficients.
We have written many articles about emissivity of materials for Universe Today. Here's an article about heat rejection systems, and here's an article about absorptivity.
If you'd like more info on emissivity, check out these articles from Engineering Toolbox and Science World.
We’ve also recorded an entire episode of Astronomy Cast all about Electromagnetism. Listen here, Episode 103: Electromagnetism.
The Sun continues to be active! This movie from the Solar Dynamics Observatory starts at 11:35 UT on March 24, 2011 and goes through midnight. It shows the active area 1176 – and active it was. Several flares are visible — according to the SDO website, there are B, C and M class flares all seen in this 20 second video. See below for another movie from March 19 of a looping solar prominence eruption on the limb of the Sun. Continue reading “Fireworks on the Sun”
At 8:30 PM on Saturday 26th March 2011, lights will switch off around the globe for Earth Hour and people will commit to actions that go beyond the hour. We need you…
Earth Hour started in 2007 in Sydney, Australia when 2.2 million individuals and more than 2,000 businesses turned their lights off for one hour to take a stand against climate change. Only a year later and Earth Hour had become a global sustainability movement with more than 50 million people across 35 countries/territories participating. Global landmarks such as the Sydney Harbour Bridge, CN Tower in Toronto, Golden Gate Bridge in San Francisco, and Rome’s Colosseum, all stood in darkness, as symbols of hope for a cause that grows more urgent by the hour.
In March 2009, hundreds of millions of people took part in the third Earth Hour. Over 4000 cities in 88 countries/territories officially switched off to pledge their support for the planet, making Earth Hour 2009 the world’s largest global climate change initiative.
On Saturday, March 27th, Earth Hour 2010 became the biggest Earth Hour ever. A record 128 countries and territories joined the global display of climate action. Iconic buildings and landmarks from Asia Pacific to Europe and Africa to the Americas switched off. People across the world from all walks of life turned off their lights and came together in celebration and contemplation of the one thing we all have in common – our planet.
Earth Hour 2011 will take place on Saturday 26 March at 8.30PM (local time). This Earth Hour we want you to go beyond the hour, so after the lights go back on think about what else you can do to make a difference. Together our actions add up.
“All over the world individuals, communities, businesses and governments are creating new examples for our common future – new visions for sustainable living and new technologies to realize it,” said UN Secretary General Ban Ki-moon. “Tomorrow, let us join together to celebrate this shared quest to protect the planet and ensure human well-being. Let us use 60 minutes of darkness to help the world see the light.”
View from a helicopter of the summit of Mauna Kea in Hawaii. Image: Nancy Atkinson
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For about 300 nights out of the year, Mauna Kea on the Big Island of Hawaii is one of the best places in the world for ground-based astronomy. At an elevation of 4,205 meters (13,796 ft), the summit sits above a large portion of the Earth’s atmosphere, and usually, the sky is clear, calm and dry. Indeed, 13 giant telescopes sit Mauna Kea’s summit, and they have made some of the biggest discoveries in astronomy. But for the remaining nights of the year, a variety of weather-related issues can keep astronomers from observing, and visitors from climbing to the summit to see those pristine skies for themselves, as well as being able to watch some of our biggest eyes on the skies action. Sometimes clouds, high winds or humidity might keep the telescope domes closed, other times snow can close the roads. On a recent visit to Hawaii, heavy snow kept the roads closed for three days and my long-planned trip to the top of Mauna Kea was, disappointingly, scrubbed. But I did get a great behind the scenes tour of the W. M. Keck Observatory headquarters in Waimea.
The Keck Headquarters and visitor center in Waimea.
While the telescopes are up at at the top of the mountain, astronomers seldom actually work at the telescopes themselves. Instead they work out of remote operations offices at the headquarters in Waimea. There is an operations room for each of the twin 10-meter Keck telescopes: Remote Operations 1 works the Keck 1 telescope:
Remote Operations Room 1 for Keck 1. Image: Nancy Atkinson
And Remote Operations 2 works Keck 2:
Remote Operations Room 2 at the Keck Headquarters. Image: Nancy Atkinson
I arrived in the morning before any of the astronomers were there. “People who work for Keck help the visiting astronomers,” said Alexandra Starr, who works with the media and is a public information officer at the Keck headquarters. “Usually, the visiting astronomers start filtering in about 2 o’clock, and the people who work on the summit get things ready for what the astronomers want to observe. There is a camera for those down here to view how things are going for getting the telescope pointed exactly where they want it.”
But the domes on the telescope can’t be opened until the sun goes down.
“So, once they get everything set up, they go for an early dinner and then come back here and observe all night long,” said Starr. “We do have people working around the clock, however. For astronomers who have been here before, sometimes they don’t need a lot of assistance, but our support astronomers will help all the visiting astronomers get the best observing they can, and get the information they need while they are on the sky.”
About 125 people work full-time at Keck, of which two-thirds are local people from from Hawaii. With an annual operating budget of $11 million, the Observatory is one of the town’s largest employers.
At the headquarters, there are condos where the visiting astronomers can stay:
Facilities where visiting astronomers stay while at Keck. Image: Nancy Atkinson
Most astronomers have just two nights for observing, and Starr said it can be up to a year and a half from when astronomers submit a proposal to use the Keck telescopes to when they actually get to observe. But sometimes, depending on the astronomer and what they are observing, they’ll get to return again fairly quickly when the weather doesn’t allow for observing.
“The past 2 nights we haven’t been observing, and those people are in town ready to go,” Starr said.
The backside of facilities includes the observatory’s own mechanics shop. “We have eight 4-wheel drive automobiles to get to the summit, and our own mechanic shop to keep them all in top shape,” Starr said.
The Keck Observatory’s headquarters in Waimea is open to visitors, and volunteer guides are available Tuesday through Friday from 10 a.m. to 2 p.m. to share information about Keck and the other Mauna Kea observatories. The visitor’s center also has a conference room for public lectures from visiting astronomers.
Inside are models and images of the twin 10-meter Keck telescopes:
Models of the twin Keck telescopes inside the Keck visitor center. Image: Nancy Atkinson
The twin Keck telescopes are the world’s largest optical and infrared telescopes. Each telescope stands eight stories tall, weighs 300 tons and operates with nanometer precision. The telescopes’ primary mirrors are 10 meters in diameter and are each composed of 36 hexagonal segments that work in concert as a single piece of reflective glass.
Outside in the visitor center courtyard is a grassy area that represents the size of just one of the hexagonal segments, which are 1.8 meters (6 ft) in diameter.
The grassy area in the courtyard of the Keck Observatory visitor center is the same size as one of the 36 hexagonal glass segments that make up the 10-meter mirrors on the two Keck telescopes. Image: Nancy Atkinson
Each segment weighs .5 metric tons (880 pounds), and are three inches thick. They are made of a glass and ceramic composite called Zerodur. Zerodur itself is not reflective, so they are covered with a thin reflective layer of aluminum.
“While the telescope is actually working it is constantly fine tuning the position of the individual mirrors to make sure they are all in alignment,” said our tour guide Rosalind Redfield.
On the telescope, each segment’s figure is kept stable by a system of extremely rigid support structures and adjustable warping harnesses. During observing, a computer-controlled system of sensors and actuators adjusts the position of each segment – relative to the neighboring segment – to an accuracy of four nanometers, about the size of a few molecules, or about 1/25,000 the diameter of a human hair. This twice-per-second adjustment effectively counters the tug of gravity.
The twin Kecks, Subaru and IRTF seen from the eastern ridge at sunset. Credit: Pablo McLoud/Keck
Up at the summit, (which I can only share pictures provided by the Keck Observatory) Redfield said it is like the other side of the Moon. “Absolutely nothing grows up there, the elevation is so high it is completely barren,” she said. “There is fine, sandy type dirt, and they don’t like people driving up there as it stirs up dust. The paved road only goes so far, and anyone driving at the summit creates enough dust that it can cause a problem, and people are only allowed to drive up if you have a four-wheel drive.”
The sun sets on Mauna Kea as the twin Kecks prepare for observing. Credit: Laurie Hatch/ W. M. Keck Observatory
Mauna Kea summit as seen from the northeast. Credit: University of Hawaii.
The two Keck telescopes and the 8.3 meter Subaru telescopes take the very top of the mountain. They are joined by the 8.1 Gemini North Telescope , the 0.6-m educational telescope, from the University of Hawaii at Hilo, a 2.2-m telescope University of Hawaii Institute for Astronomy, the 3 meter NASA Infrared Telescope Facility, the 3.6 meter Canada-France-Hawaii Telescope, the 3.8 meter UKIRT (United Kingdom Infrared Telescope), the 10.4 Caltech Submillimeter Observatory, the 15 meter James Clerk Maxwell Telescope, the 8X6 meter Submillimeter Array and the 25 meter Very Long Baseline Array.
A map of the telescopes on Mauna Kea. Credit: University of Hawaii.
But, no climb to the summit for me — not this time anyway! I hope to return one day to Mauna Kea to see first-hand where science and nature come together to allow for continued discovery of our universe.
Clouds and snow obscure the summit of Mauna Kea as I drive away, after a climb to visit the Keck telescopes was nixed. Image: Nancy Atkinson.
For more information about the Keck Observatory, see their website, and if you are in Hawaii or going to be visiting the Big Island, find information here on how you can visit the Observatory headquarters, or go to the summit.
